Conventional and Internet protocol (“IP”) private branch exchanges (“PBXs”) are typically connected to the public switched telephone network (“PSTN”) through time-division multiplexing (“TDM”) integrated services digital network (“ISDN”) primary rate interface (“PRI”) circuits. Customers typically purchase IP PBXs that have Calling Name Delivery (“CNAM”) as a feature. CNAM is a service that displays a caller's name on the calling party's digital readout on their telecommunications device. This is similar to the Caller ID service, but that the calling party's name is displayed along with their calling number or instead of the calling number. The customer pays a fee for the service, which can be anywhere from $50-$90 per PRI per month for the CNAM. To deliver the CNAM to the IP PBX, the customer's telecommunications provider, such as an incumbent local exchange carrier (“ILEC”) or competitive local exchange carrier (“CLEC”), may launch a CNAM query when a call is destined for the PRI trunk group. The ILEC/CLEC may then deliver the CNAM information via the signaling “D” channel on the PRI. Currently, the IP PBXs connected to the PSTN via PRIs do not have the functionality of launching a query for CNAM information via IP. Typically, the ISDN PRI circuits are purchased from the ILEC/CLEC in an operating region and they generally provide connectivity to the PSTN for both media and signaling traffic.
Current IP PBXs rely on the network of the ILEC/CLEC to query hosted databases for CNAM and other information. In a typical operation, a call setup is attempted for an inbound call and the PRI is equipped with CNAM Delivery, so the ILEC/CLEC Class 5 switch launches a CNAM query to either its database, or to a database provider with whom it has a contract. The database or database provider may be part of or accessed through a signaling transfer point (“STP”) or switching control point (“SCP”); this query may either be in IP or TDM format. Generally, the database is queried based on an incoming telephone number and an associated name is delivered to the ILEC/CLEC Class 5 switch. The Class 5 switch passes the CNAM information to a PBX via the SS7 packet, for example. At the PBX, the CNAM data is eventually delivered to the appropriate station on the customer's premise, after which the call takes place.
Typically, the CNAM information is delivered in the SS7 transaction capabilities access part (“TCAP”) portion of the packet along with other call setup information, such as parameter set identifier, parameter length, generic name, generic name length, presentation, spare, availability, type of name, and name, for example.
Telephone number mapping or electronic number mapping (“ENUM”) is a suite of protocols that unify the telephone numbering system E.164 with the Internet addressing system domain name system (“DNS”) by using indirect lookup method to obtain naming authority pointer (“NAPTR”) methods. ENUM resolves addressing of telephone numbers to a uniform resource locator (“URL”). If an ENUM query is launched based on the outbound telephone number, then the response may include all URL addresses of the devices (e.g., Instant Messaging (“IM”), fax, mobile, etc.) associated with the telephone numbers. Currently, IP PBXs must rely on their servicing ILEC/CLEC to launch ENUM queries, if desired. Generally, ENUM is used today in voice over internet protocol (“VoIP”) Peering Exchanges and for inter-carrier multimedia messaging services (“MMS”) routing. ENUM queries launched in IP PBXs via IP connections may provide outbound calls to be routed by IP instead of TDM, and can provide information necessary to support inter-carrier enhanced IP services, such as find-me/follow-me service.